<template>
  <!-- 鼠标移入清空定时器（不允许自动播放），鼠标离开（继续自动播放） -->
  <div class="xtx-carousel" @mouseenter="stop" @mouseleave="play">
    <ul class="carousel-body">
      <li
        class="carousel-item"
        :class="{ fade: active === index }"
        v-for="(item, index) in slides"
        :key="item.id"
      >
        <RouterLink to="/">
          <img :src="item.imgUrl" alt="" />
        </RouterLink>
      </li>
    </ul>
    <a href="javascript:;" class="carousel-btn prev" @click="prev"
      ><i class="iconfont icon-angle-left"></i
    ></a>
    <a href="javascript:;" class="carousel-btn next" @click="next"
      ><i class="iconfont icon-angle-right"></i
    ></a>
    <div class="carousel-indicator">
      <!-- 鼠标经过圆点，把圆点的下标赋值给active（下标高亮） -->
      <span
        :class="{ active: active === index }"
        v-for="(item, index) in slides"
        :key="item.id"
        @mouseenter="active = index"
      ></span>
    </div>
  </div>
</template>

<script>
import { onMounted, onUnmounted, ref } from 'vue'
export default {
  name: 'XtxCarousel',
  props: {
    slides: {
      type: Array,
      // 复杂属性需要用函数返回
      default: () => []
    },
    // 是否自动播放
    autoPlay: {
      type: Boolean,
      default: false
    },
    // 轮播图切换时间
    duration: {
      type: Number,
      default: 3000
    }
  },
  setup(props, { emit }) {
    // 轮播图高亮下标默认等于0
    const active = ref(0)
    // 轮播图播放逻辑
    let timer = null
    const play = () => {
      // 如果没传，默认是false，false就不用执行轮播图播放的逻辑
      if (!props.autoPlay) return
      // 防止开启多个定时器,进来就清除定时器
      clearInterval(timer)
      timer = setInterval(() => {
        // 如果下标要溢出了，就把下标变成0，这样就可以从第一张开始
        if (active.value >= props.slides.length - 1) {
          active.value = 0
        } else {
          // 否者就自动加1，播放下一张图片
          active.value++
        }
      }, props.duration)
    }
    // 上一张
    const prev = () => {
      if (active.value <= 0) {
        active.value = props.slides.length - 1
      } else {
        active.value--
      }
    }
    // 下一张
    const next = () => {
      if (active.value >= props.slides.length - 1) {
        active.value = 0
      } else {
        active.value++
      }
    }
    const stop = () => {
      clearInterval(timer)
    }
    // 组件渲染时，开启轮播图
    onMounted(() => {
      play()
    })
    // 组件销毁时，关闭轮播图
    onUnmounted(() => {
      stop()
    })
    return {
      active,
      play,
      stop,
      prev,
      next
    }
  }
}
</script>
<style scoped lang="less">
.xtx-carousel {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel {
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background: #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, 0.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev {
        left: 20px;
      }
      &.next {
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>
